For the asparagus and potato salad, boil the potatoes and let cool. Cut the leek into fine strips. Cut the peeled potatoes and the peeled apple into small cubes. Marinate with oil, vinegar, salt, sugar and the leek.
Briefly overcook the asparagus and cut into pieces about 1 cm long. Fold in together with the remaining ingredients. Leave the asparagus and potato salad to stand for at least 1 hour.